Untitled

import java.util.Scanner;
import java.util.concurrent.Semaphore;

public class ReaderWriter {
static Semaphore mutex = new Semaphore (1);
static Semaphore wrt = new Semaphore(1);
static int readCount = 0;
static String message = "hello";
static Scanner sc = new Scanner(System.in);
static class Reader implements Runnable
{       //Reader Thread
    public void run ()
    {
        try{
            //acquire section
            mutex.acquire(); 
            readCount++;
            if (readCount == 1)
            {
                wrt.acquire();
            }
            mutex.release();
            System.out.println("thread"+ Thread.currentThread().getName()+"is reading:" + message);
            Thread.sleep(1500);
            System.out.println("thread"+ Thread.currentThread().getName()+"has finished reading");
            //releasing section
            mutex.acquire();
            readCount--;
            if(readCount == 0)
            {
                wrt.release();
            }
            mutex.release();
        } catch(InterruptedException e)
        {
            System.out.println(e.getMessage());
        }
    }

}
static class Writer implements Runnable
{
    public void run()
        {
            try 
            {
                wrt.acquire();
                message = "Good Morning";
                System.out.println("thread"+ Thread.currentThread().getName()+"is reading:" + message);
                Thread.sleep(1500);
                System.out.println("thread"+ Thread.currentThread().getName()+"has finished reading");
                wrt.release();
            }
            catch (InterruptedException e)
            {
                System.out.println(e.getMessage());
            }
        }
}
//main program
    public static void main(String[] args) throws Exception
    {
        Reader read = new Reader();
        Writer write = new Writer();
        Thread r1= new Thread(read);
        r1.setName("Reader1");
        Thread r2= new Thread(read);
        r2.setName("Reader2");
        Thread r3= new Thread(read);
        r3.setName("Reader3");
        Thread w1 = new Thread(write);
        w1.setName("Writer1");
        Thread w2 = new Thread(write);
        w2.setName("Writer2");
        Thread w3 = new Thread(write);
        w3.setName("Writer3");
        w1.start();
        r1.start();
        w2.start();
        r2.start();
        w3.start();
        r3.start();
    }
}